1. Field of the Invention
The present invention relates to valves for use with fluid systems and particularly to a center guided check valve.
2. Description of the Prior Art
An ongoing challenge in the design of backflow check valves is to meet all applicable industry standards while maintaining the lowest possible pressure loss through the valve. Heretofore, manufacturers of check valves have designed and manufactured check valves that include a center guide urged to a closed position by a compression spring. While this design is very reliable, there is greater pressure loss across the valve because of the direct load imposed by the spring. Some manufacturers have attempted to reduce pressure drop by using a flapper-style check valve design having a spring to urge the flapper to a closed position. This design has proven unreliable due to the lack of precision in guiding the check valve to the seat. In an effort to mechanically reduce the spring load, a single torsion spring has been used in conjunction with the flapper-type check valve. This design provides reduced pressure loss through the valve but suffers the same reliability problems as other flapper-type check valve designs.
It is an object of the present invention to provide a check valve that overcomes the disadvantages present in these prior art check valves.
It is a specific object of the present invention to provide a check valve in which the spring load on the valve seal in the open position does not cause significant pressure loss across the valve.